internal/pkg: override working directory perms

This must be writable to enable renaming, and the final result is conventionally read-only alongside the entire directory contents. This change overrides the permission bits as part of Store.

Signed-off-by: Ophestra <cat@gensokyo.uk>

internal/pkg/pkg_test.go

@@ -455,7 +455,7 @@ func TestCache(t *testing.T) {
 			} else if !store {
 				t.Fatal("Store did not store nonpresent entry")
 			}
-		}, pkg.MustDecode("N7dntFYbOq9V4iC-rjAQ-By6ofPIQVZkA8V0r0G07M_sdB7Zh42Ttrspsc38ioYa")},
+		}, pkg.MustDecode("8OP6YxJAdRrhV2WSBt1BPD7oC_n2Qh7JqUMyVMoGvjDX83bDqq2hgVMNcdiBH_64")},
 	}
 	checkWithCache(t, testCases)
 }